Crotonylome profiling reveals extensive lysine crotonylation in common wheat

Histone lysine crotonylation (Kcr) is a newly discovered protein post-translational modification (PTM), which was detected from yeast to humans and is mainly related with active transcription. With the development of proteomics technologies, high abundance of non-histone proteins modified by Kcr was also found recently. Here, we first report that lysine Kcr also occurs on cytoplasmic and mitochondrial proteins in common wheat (Triticum aestivum L.). We identified 4,696 Lys-acetylated sites on 1,726 proteins which involved in a wide variety of biological processes, such as chromatin-associated processes, Calvin-Benson cycle, glycolysis, protein metabolism and transport, which representing the largest dataset of lysine acylation proteome reported in the plant kingdom. Interestingly, 98 proteins were involved in multiple processes of photosynthesis, suggesting an important role of lysine Kcr in processes. In addition, 21 potentially specific Kcr motifs in wheat were detected. The protein interaction network analysis revealed that diverse interactions are modulated by protein Kcr. The overlap between Kcr and acetylation (Kac) indicated that they may coordinately regulate the function of some proteins in common wheat. Futhermore, comparative analysis indicated that lysine Kcr is conserved between common wheat and Nicotiana tabacum. Taken together, this study provided the first global survey of Kcr in wheat, making a promising starting point for further functional analysis of Kcr in plants.

组蛋白赖氨酸巴豆酰化（Histone lysine crotonylation, Kcr）是一类新近发现的蛋白质翻译后修饰（post-translational modification, PTM），该修饰已在酵母至人类等多种生物中被检测到，且主要与活跃转录过程相关。随着蛋白质组学技术的发展，近期研究亦发现了大量经Kcr修饰的非组蛋白。本研究首次报道，在普通小麦（Triticum aestivum L.）的细胞质与线粒体蛋白质中同样存在赖氨酸巴豆酰化修饰。本研究共在1726个蛋白质上鉴定到4696个赖氨酸乙酰化位点，这些蛋白质参与了包括染色质相关过程、卡尔文-本森循环、糖酵解、蛋白质代谢与转运在内的多种生物学过程，该数据集为目前植物界已报道的最大规模赖氨酸酰化修饰蛋白质组数据集。有趣的是，其中98个蛋白质参与了光合作用的多个过程，这提示赖氨酸巴豆酰化修饰在该生命活动中发挥重要作用。此外，本研究还在普通小麦中鉴定到21个潜在的特异性Kcr基序。蛋白质相互作用网络分析结果显示，蛋白质的多种相互作用均受赖氨酸巴豆酰化修饰的调控。赖氨酸巴豆酰化与乙酰化（Kac）的修饰位点重叠现象提示，二者可能在普通小麦中协同调控部分蛋白质的功能。此外，比较蛋白质组分析结果显示，赖氨酸巴豆酰化修饰在普通小麦与烟草（Nicotiana tabacum）中具有保守性。综上，本研究首次完成了普通小麦中赖氨酸巴豆酰化修饰的全景式分析，为后续植物中赖氨酸巴豆酰化修饰的功能研究提供了极具前景的研究起点。